Food product with a fibrous texture obtained from whey proteins

ABSTRACT

Food product obtained by extrusion baking of a mixture of dairy or cheese origin with a fibrous structure characterized in that the fibers form a network of macroscopic fibers whose diameters are in the order of 0.1 mm to 1 mm, ramified into microscopic fibers with diameters in the order of 1 μm to 0.1 mm, with the dry matter of the product at least partially originating from whey.

CROSS-REFERENCE TO RELATED APPLICATIONS

This present application is a divisional of U.S. patent application Ser.No. 09/590,979 filed Jun. 9, 2000 now U.S. Pat. No. 6,468,579, claimingpriority to French Patent Application Serial No. 9907433 filed Jun. 11,1999, both of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention concerns food products with a fibrous texture,obtained mainly from whey proteins, a manufacturing process by extrusionbaking of these products and a manufacturing installation forapplication of the process.

BACKGROUND OF THE INVENTION

Processes for the manufacture of dairy products by continuous extrusionare already known.

Document EP-A-727 138 describes one such extrusion process by means ofwhich cheese or cheese products are obtained from a curd or milkfraction resulting from ultrafiltration of milk. The process iscomprised of the following stages: introduction of raw materials,transfer into a barrel with at least one zone in which the temperatureis between 60° and 120° C. involving blending, texturing and baking.This process gives rise to products with stretched structures whosefibres have a diameter that is generally greater than 0.1 mm and in theorder of millimeters.

Document WO-96/34 539 describes a process used to obtain a texturedprotein matrix containing a dispersion of inclusion bodies. Theseproducts are obtained by means of a high-temperature extrusion process,notably at temperatures of 125 to 160° C. High temperatures such as thislead to the destruction of the initial protein mixture. The productsobtained include protein fibres which are stable after cooling. Thisdocument essentially describes the use of vegetable proteins such assoya.

Document WO-96/25051 describes a process for the manufacture of a softor semi-soft fibrous cheese. The fibrous mass is obtained afterextrusion of the curdled milk. These processes do not allow a cheese ormilk mixture to be used to obtain a product with an extremely finefibrous structure, comprising fibres whose sizes are in the range of μmto 0.1 mm, noticeable when the product is chewed and conferring on itoriginal organoleptic characteristics.

Document U.S. Pat. No. 4,156,028 also describes a process for themanufacture of fibre products whose fibres have diameters in the orderof 100 μm for example. However, these products are obtained by atechnique which involves dissolution followed by a coagulation bath; theprinciples and materials of this technique are considerably differentfrom extrusion baking which brings together specific pressure andtemperature features. The products obtained do not have a ramifiednetwork structure such as that described below.

SUMMARY OF THE INVENTION

The present invention concerns food products with a fibrous texture,obtained mainly from whey proteins, a manufacturing process by extrusionbaking of these products and a manufacturing installation forapplication of the process. A first aspect of the invention proposes aproduct obtained by extrusion baking of a mixture of dairy or cheeseorigin. This product has a fibrous structure with a network ofmacroscopic fibres whose diameters are in the order of 0.1 mm to 1 mm,ramified into microscopic fibres with diameters in the order of 1 μm to0.1 mm, the dry matter in the product being at least partially obtainedfrom whey. The dry matter in the product typically comprises 30% to 100%of dry matter originating from whey. The product consists of 15 to 50%of dry matter and typically 25 to 40%. The dry matter of the productconsists of at least 35% of total proteins. The dry matter originatingfrom whey includes isolated and/or concentrated proteins, and/or driedwhole whey, and/or dried whey fractions such as lactose, milk fats,lactoferrin, calcium or other milk minerals or fractions.

According to a second aspect, the invention concerns a food preparationincorporating a product in keeping with the description above added tovarious ingredients chosen from among cheeses, milk and derivativeproducts (yoghurt, milk cream, milk powder, fromage blanc, butter),cereals, starches, flour, semolina, fruits and dried fruits, spices,seasoning, fats, flavouring, sugar-containing ingredients (sugar,honey), pieces of meat or fish or vegetables, so as to form ready-mademeals, children's snacks, sandwiches, snack foods, breakfast products,burger- or sausage-shaped cheese products, vegetarian products, spreads,pate and cooking ingredients.

According to a third application, the invention concerns a process forthe manufacture of products with a fibrous structure comprised of thefollowing steps:

a) introduction of raw materials containing whey proteins into anextruder with at least one screw;

b) transfer of raw materials from one end to the other of the extruderbarrel, adjusting the screw(s) and temperature within the barrel suchthat raw materials successively undergo a mixing and heating step up toa temperature of about 130° C., followed by a melting step with anincrease in temperature of the material to above 130° C., generallybetween 140° C. and 200° C., and an increase in pressure to between 0and 50 bars, such that plasticization of the transferred material takesplace, especially of whey proteins;

c) extrusion at the far end of the barrel of the material obtained afterplasticization through a die adapted for texturization, shaping andcooling the material such that a product with a fibrous structure isobtained.

The process also includes a cutting step at the outlet of the die.According to one application, it includes a step where the product isdried at the outlet of the die after cutting to produce rehydratablefibres for food preparations if need be. It can also include a shapingstep comprised of mechanical forming processes using a shaper or mouldsor piping followed by pasteurisation and slicing, with, the productsobtained undergoing at least one of the following steps: decoration,coating, stamping, filling, frying, baking, pasteurisation,sterilisation, packaging.

According to a fourth aspect, the invention concerns a manufacturinginstallation for the application of the process presented abovecomprised of a screw extruder with two very similar interlocking screwswhich rotate in the same direction or in the opposite direction inside ahorizontal barrel, a filling device attached at the near end of thebarrel, fitted with one or more metering devices for metered flow of themixture at a predetermined rate, an extrusion die located at the far endof said barrel, thermal treatment assembly for fine-tuning thetemperature within the barrel and extrusion die, said barrel beingcomprised of:

(a) a first zone for supply of the product formula;

(b) a second zone for mixing, moisturisation where this is required, andheating the material up to a core temperature of at least 130° C.;

(c) a third zone for melting, increasing the temperature of the materialto over 130° C., generally between 140 and 200° C. and pressure of thematerial to between 0 and 50 bars, depending on the composition of theformula, in which protein plasticization takes place, especially of wheyproteins. Further areas of applicability of the present invention willbecome apparent from the detailed description provided hereinafter. Itshould be understood that the detailed description and specificexamples, while indicating the preferred embodiment of the invention,are intended for purposes of illustration only and are not intended tolimit the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 illustrates an installation for the manufacture of ultrafibresaccording to a high-temperature and high-moisture extrusion process,according to one mode of application;

FIG. 2 illustrates an installation for the manufacture of ultrafibresaccording to a high-temperature and high-moisture extrusion process,according to another mode of application;

FIGS. 3 and 4 represent extruded fibre products after chopping, at theoutlet of the extrusion die;

FIG. 5 represents magnification of a transverse cut of an isolatedbundle of fibres as in FIGS. 3 or 4;

FIG. 6 represents magnification of a fragment of product leaving theextrusion die, with fibres shown by manual extension (×10magnification);

FIGS. 7 and 8 represent food preparations developed from extruded fibreproducts incorporated into a mixture including other constituents, inparticular cereals. FIG. 8 is a magnification of the core of the fibrebundle in FIG. 7.

FIG. 9 is a further magnification of a zone showing isolated fibres inFIG. 8 (each graduation represents 1 mm).

DETAILED DESCRIPTION OF THE INVENTION

The following description of the preferred embodiment(s) is merelyexemplary in nature and is in no way intended to limit the invention,its application, or uses.

To this end, a first aspect of the invention proposes a product obtainedby extrusion baking of a mixture of dairy or cheese origin. This producthas a fibrous structure with a network of macroscopic fibres whosediameters are in the order of 0.1 mm to 1 mm, ramified into microscopicfibres with diameters in the order of 1 μm to 0.1 mm, the dry matter inthe product being at least partially obtained from whey. The dry matterin the product typically comprises 30% to 100% of dry matter originatingfrom whey. The product consists of 15 to 50% of dry matter and typically25 to 40%. The dry matter of the product consists of at least 35% oftotal proteins. The dry matter originating from whey includes isolatedand/or concentrated proteins, and/or dried whole whey, and/or dried wheyfractions such as lactose, milk fats, lactoferrin, calcium or other milkminerals or fractions. According to one application, the productcontains, in addition to whey proteins, other protein fractions such ascasein or caseinates, cheese, dried or concentrated milk, with drymatter from the product preferably comprised of at least 10% casein.

According to another application, the product contains, in addition towhey proteins, non-dairy proteins chosen from among concentrated orisolated vegetable proteins, especially wheat, soya or pea gluten,liquid or dry egg white, with non-dairy proteins representing 0 to 70%of the mixture's dry matter, and preferably 20 to 50%.

According to a second aspect, the invention concerns a food preparationincorporating a product in keeping with the description above added tovarious ingredients chosen from among cheeses, milk and derivativeproducts (yoghurt, milk cream, milk powder, fromage blanc, butter),cereals, starches, flour, semolina, fruits and dried fruits, spices,seasoning, fats, flavouring, sugar-containing ingredients (sugar,honey), pieces of meat or fish or vegetables, so as to form ready-mademeals, children's snacks, sandwiches, snack foods, breakfast products,burger- or sausage-shaped cheese products, vegetarian products, spreads,pate, and cooking ingredients.

According to one application, the food preparation has a matrixcomprised of fibres or bundles of fibres with sizes in the range of mmor μm, with the preparation having dimensions in the order of a fewcentimeters. The preparation undergoes mechanical forming, metering,shaping in moulds or piping then pasteurised and sliced. Thepreparations obtained can be decorated, stamped, cooked or pre-cooked,pasteurised, sterilised and packaged.

According to one application, the preparation contains a product inaccordance with the description above which encloses a dairy ornon-dairy filling product. According to another application, thepreparation contains a product in accordance with the description aboveenclosed by a dairy or non-dairy coating product. The preparation canalso include salts, spices, seasoning and flavouring, oil or other fats,an acidity corrector such as lactic acid. According to a thirdapplication, the invention concerns a process for the manufacture ofproducts with a fibrous structure comprised of the following steps:

a) introduction of raw materials containing whey proteins into anextruder with at least one screw;

b) transfer of raw materials from one end to the other of the extruderbarrel, adjusting the screw(s) and temperature within the barrel suchthat raw materials successively undergo a mixing and heating step up toa temperature of about 130° C., followed by a melting step with anincrease in temperature of the material to above 130° C., generallybetween 140° C. and 200° C., and an increase in pressure to between 0and 50 bars, such that plasticization of the transferred material takesplace, especially of whey proteins;

c) extrusion at the far end of the barrel of the material obtained afterplasticization through a die adapted for texturization, shaping andcooling the material such that a product with a fibrous structure isobtained.

Cooling takes place in the die to a temperature of 100° C., possiblyeven between 80° C. and 10° C., and consists of an initial cooling phasein an uncooled zone in the die at the outlet of the barrel, followed bya second cooling phase in a cooled zone of the die. The first coolingphase corresponds to an alignment zone of the melted mixture which is ina viscous state and has a viscosity of 1000 to 500000 centipoises whilethe second cooling phase corresponds to a change of state from theviscous state to the solid state, the linear flow rate of the product atthe outlet of the die being in the order of 2 to 10 m/min. Heating to130° C. in step b) is gradual or in stages. The temperature can beadjusted during the process to modify the texture of products. Themixture placed in the extruder is in the form of a powder, with all therequired water added prior to the melting step, or in liquid or pasteform.

According to one application, the whey proteins originate from wheyprotein concentrates or isolates which are 50 to 90% pure, preferably 70to 80% pure, and also contain lactose, fats, minerals, secondaryproteins of the casein macropeptide type. The process also includes acutting step at the outlet of the die such as chopping, slicing,crushing, tearing, shredding or similar to obtain chopped fibres formingflakes or bundles. According to one application, it includes a stepwhere the product is dried at the outlet of the die after cutting toproduce rehydratable fibres for food preparations if need be. Theprocess can also include a culinary reconstitution step using choppedfibres mixed with various ingredients such as cheese, milk andderivative products, cereals, starches, flour or semolina, fats, spices,seasoning and flavouring.

It can also include a shaping step comprised of mechanical formingprocesses using a shaper or moulds or piping followed by pasteurisationand slicing, with the products obtained undergoing at least one of thefollowing steps: decoration, coating, stamping, filling, frying, baking,pasteurisation, sterilisation, packaging. According to one application,the material transferred to the die is filled with a filling productduring the extrusion step, added through the coextrusion valve openinginto the die. The filling product can be obtained by means of anextrusion process.

According to a fourth aspect, the invention concerns a manufacturinginstallation for the application of the process presented abovecomprised of a screw extruder with two very similar interlocking screwswhich rotate in the same direction or in the opposite direction inside ahorizontal barrel, a filling device attached at the near end of thebarrel, fitted with one or more metering devices for metered flow of themixture at a predetermined rate, an extrusion die located at the far endof said barrel, thermal treatment assembly for fine-tuning thetemperature within the barrel and extrusion die, said barrel beingcomprised of:

(a) a first zone for supply of the product formula;

(b) a second zone for mixing, moisturisation where this is required, andheating the material up to a core temperature of at least 130° C.;

(c) a third zone for melting, increasing the temperature of the materialto over 130° C., generally between 140 and 200° C. and pressure of thematerial to between 0 and 50 bars, depending on the composition of theformula, in which protein plasticization takes place, especially of wheyproteins.

The second mixing and heating zone consists of 2 to 5 units, the thirdmelting zone comprises 1 to 3 units, with a screw length to screwdiameter ratio of about 10 to 33, typically between 25 and 33. Theextrusion die includes a first uncooled zone adjacent to the near end ofthe screw extruder, followed by at least one cooling zone, correspondingto an alignment zone for fibres in a viscous state and a change-of-phasezone from the viscous to solid state.

The die is connected to the barrel by means of at least one, andtypically two, adapters. The first adapter has one or two perforationsthrough which the melted and plasticized material is extruded; thesecond adapter is located between the first adapter and the extrusiondie and its function is to balance materiel pressure and flow rate. Theextrusion die has an internal shape that is adapted to the finalproduct, with size parameters designed to allow cooling of the meltedand plasticized material to 100° C., possibly between 80 and 10° C. Itsinner surface has a controlled roughness in order to exert shear forceson the product during the cooling process, the combination of coolingand shear forces leading to continuous texturization of the cooledmaterial to form fibres.

The installation can include an extrusion pump located, for example,between the first or second interface and die for steady supply to thedie in order to stabilise product flow. This is often a gear pump whosebody can be reheated by electrical resistances in order to maintain amelted and plasticized mass at the required temperature. According toone application, a coextrusion valve opens into the extrusion die.

A description of a manufacturing installation for application of theprocess leading to the production of fibrous dairy products is givenbelow. The installation comprises a screw extruder 1 with two verysimilar interlocking screws which rotate in the same direction or in theopposite direction inside a barrel 2. A single screw extruder is alsopossible. Such an extruder consists of a motor 3 which drives therotation of the two screws, interlocked by means of a reduction gear ifnecessary. Rotation is powered at a rate of 25 to 100 kW for example.These screws are preferably self-cleaning and the barrel 2 can beshifted manually or hydraulically along its longitudinal line tofacilitates access to the screws. The materials used to manufacture thebarrel 2 and screws are obviously food grade materials.

A filling valve 4 is located towards the near end 5 of the barrel. Thisvalve 4 is used to introduce raw materials to be processed into thescrew extruder 1. The barrel can also include openings for secondarysupply along the line of the screws, for example for supply of water. Anextrusion die 7 is located at the far end 6 of the barrel 2. A cuttingdevice 8, and where necessary recovery device, are placed at the outletof the extrusion die. According to established practices, the extrusiondie 7 has a smaller diameter than the bore diameter of the barrel suchthat transferred materials are compressed. In the case of continuousproduction, the installation comprises a metering device to feed rawmaterials into the filling valve 4 at a predetermined flow rate. Heating8 a and cooling devices are adjusted to regulate temperature inside thebarrel 2 and extrusion die 7.

The structure of the barrel 2 and extrusion process will be describedbelow in more detail. The term “mixture” is used to describe rawmaterials subjected to the steps in the process which take place afterintroduction of the materials, that is to say the heating, mixing andmelting steps. The barrel 2 consists of 3 adjacent zones 9, 10, 11. Thefirst, zone 9, is a filling zone into which the raw materials to beextruded are introduced. The filling valve 4 for the mixture opens here.According to one application, these raw materials are in the form of asolid powder and are added through the filling valve, along with water.The water for the mixture is added in the filling zone either totally orpartially, or can be added in the second zone 10. According to anotherapplication, the raw materials are in liquid form and are added throughthe filling valve 4, in the case, for example, of liquid dairy products.According to yet another application, the raw materials are in the formof a paste in the case of a cheese preparation such as ground curd,added through the filling valve, with water added in the filling zoneand/or the second zone 10 where necessary. All the water in the mixtureis added prior to the melting step. The composition of the mixture isgiven later.

The second zone 10 is where mixing, or moisturisation where necessary,and heating to at least 130° C. take place. The mixture is transferredfrom one end to the other of the barrel 2 while being exposed tocompression and shear forces, in addition to being heated, as will bedescribed later on. The third zone 11 is the melting zone, with thetemperature of the material increased to over 130° C., generally between140° C. and 200° C., and the pressure increased to between 0 and 50bars, depending on the composition of the formula, especially moisturecontent. Thermo-mechanical treatment which takes place in the third zone11 is sufficient to cause the majority of food products to melt,especially whey proteins which undergo a plasticization step. Theplasticization step and its effects on the final product will bedescribed in detail at a later point.

One application of the barrel 2 will now be described in more detail.This involves the first 9, second 10 and third 11 zones. These zonesinclude at least one 200 or 250 mm unit. Each barrel unit has aspecific, preregulated temperature. Depending on the prescribedtemperature, heating is more or less continuous and gradual. Thetemperature of each unit can be regulated during the course of theprocess, depending on the raw materials added and the products requiredat the outlet of the die. The first zone 9 is comprised of a unit 12 inwhich the temperature is equal to the autogenous temperature of themixture entering the extruder.

According to one variation, the second zone 10 has three units 13 andthe third zone 11 has three units 14. The temperature of the units 13 inthe second zone 10 is 90, 100, 140° C. respectively, from one end of thebarrel 2 to the other. The temperature in the units 14 in the third zone11 is 165, 175, 175° C. respectively, from one end of the barrel 2 tothe other.

According to a second variation, the second zone 10 has five units 13providing gradual heating in five stages from one end of the barrel tothe other. The third zone 11 has three units 14 as in the firstvariation of the application. According to a third variation, the secondzone 10 only has two units 13 and heating is, as a result, less gradualthan in the first and second variations. The melting zone 11 has onlyone unit 14.

In the same way as the barrel being comprised of several units eachcorresponding to a given temperature, the barrel screws also consist ofseveral elements. Each of these elements has a given structure, from oneend to the other. The length of each series of elements may or may notcoincide with the length of a unit.

In one application, the diameter D of screw elements is 55.3 mm and thelength of each element is 50, 100 or 200 mm. The total length L of screwelements mounted on a screw shaft is 1000 mm, in other words an L/Dratio of 18. This ratio ranges from 14, in the case of four 200-mm unitsin the barrel, as in the third application, to 33 in the case of nine200-mm units, as in the second application. This ratio is, for example,25 in the case of seven 200-mm units. According to one application, thebarrel 2 of the extruder 1 consists of five 200-mm units, four of whichare heated and/or cooled to achieve a precisely regulated temperature,notably by successive heating and heat extraction.

The elements of the single-thread screw are called V1F (pitch in mm).The elements of the double-thread screw are called V2F (pitch in mm).The elements of mixing screws are called MAL (angle in degrees) whilethe elements of negative-thread screws are called NEG (pitch in mm,number of perforations per thread×dimension in mm). In a usualapplication, the profile of the two screws is as follows:

200 mm filling zone: 200 mm V2F (50 mm);

500 mm mixing and heating zone: 100 mm V1F (50 mm)+50 mm MAL (90°)+150mm VIF (33 mm)+50 mm MAL (60°)+100 mm V1F (25 mm)+50 mm NEG (−15 mm, 3×6mm);

300 mm melting zone: 150 mm V1F (33 mm)+150 mm V1F (25 mm).

This is only one example of an application of the invention. There aremany more combinations of screw profiles that can be implemented usingthe same screw elements or other screw elements of a similar design. Inthe case of this profile, in the 500 mm mixing and gradual heating zone,the screw has elements of mixing screws and elements of the VIF screw ofdecreasing thread size (50 then 33 then 15 mm), leading to gradualcompression of treated materials.

A description of the die 7 is given below. The die 7 typically consistsof several die elements positioned end to end and connected by means ofadapted mechanical attachments. Its size is adapted to provide gradualcooling of the melted and plasticized material, to a temperature of 100°C., if not less, for example to a temperature of 10° C., preferablybetween 80 and 30° C. The internal surface of the die 7 has a controlledroughness obtained, for example, by machining the internal metal surfaceof the die in order to exert shear forces on the product during thecooling process. The internal shape of the die is adapted to the finalproduct required.

The combination of cooling and shear forces on the walls applied duringthe liquid-to-solid change of state leads to texturization of thematerial in the form of fibres as described below. In some cases, theshear forces on the walls and the length of the die can be sufficientlyhigh to allow extrusion of the product without the need for auxiliarycooling outside the die. In the majority of cases, the die 7 includes acooling system for the outer surface, for example by circulation of coldwater in a double sleeve (water between 60° C. and 0° C.). It is alsopossible to cool the die 7 by means of brine at negative temperature(−1° C. to −20° C.). The combination of cooling temperature in the dieand shear forces on the inner walls of the die 7 is very much dependenton the shape of the die, its length, constituent materials and machiningas well as on the characteristics (temperature, moisture, . . . ) andflow rate of the melted material to be cooled down.

According to a first application, the die is a round die made of 316 Lstainless steel with a 325 mm² flow section allowing 100 kg/hour ofmaterial to be textured over a length of 8 m (8 zones of 1 m each).Cooling is carried out using ice water at 1° C. circulating at a rate of500 liters/hour. The moisture content of the extruded mixture is about72%.

According to a second application, the die is a rectangular die made of316 L stainless steel with a 1200 mm² flow section allowing 350 kg/hourof material to be textured over a length of 6 m (6 zones of 1 m each).Cooling is carried out using ice water at 20° C. circulating at a rateof 1000 liters/hour. The moisture content of the extruded mixture isabout 62%. The linear speed of product discharge from the die 7 is about2 to 10 meters/minute. The die 7 consists of a first uncooled zone 15,which lengthens the far end of the melting zone 11, and at least asecond zone 16 cooled by the device above. The temperature of theproduct discharged from the die is 10 to 100° C. depending on thedesired rigidity. In a first application for example, the uncooled zone15 has a length of 2 meters.

According to one mode of application, the installation has a firstadapter between the far end 6 of the melting zone 11 and the extrusiondie 7. This first adapter generally consists of one (or two)perforation(s) through which the melted and plasticized material isextruded. If there are two perforations, these converge in a singleoutlet. If the extrusion die has a small diameter, the perforations aregenerally conical. The first adapter often has two lateral perforationsinto which probes for measuring melting temperature Tm and pressure Pare inserted. The outlet of the first adapter can be round, oval,square, rectangular or with the exact internal shape of the extrusiondie (this can be a ludic shape).

According to one application, in addition to the first adapter, theextruder comprises a second adapter between the first adapter and theextrusion die. This second adapter can have various internal shapesdepending on the internal shape of the first adapter and extrusion die.It can incorporate a diffusion plate consisting of several dozen smallperforations which distribute the flow of melted and plasticizedmaterial. In general, the total surface area of perforations in thediffusion plate is set up so as to create a restriction of 10 to 50%with respect to the flow section in the extrusion die.

According to one application, the extrusion pump is inserted between thesecond adapter and the die in order to allow steady flow into the diefor improved stabilisation of flow. Furthermore, several cooling diescan be arranged in parallel at the outlet of the screw barrel.

The impact of thermo-mechanical treatment in the extruder of productsleaving the die will now be described. Due to the high temperatures usedin the melting zone, the thermo-coagulable constituents of the mixtureundergo plasticization. The term thermo-coagulable proteins refers toproteins such as whey proteins, egg white, globulins, fish or meatmuscle proteins as opposed to non-thermo-coagulable proteins such ascaseins or collagen. These thermo-coagulable proteins have the propertyof gelling or coagulating around 50-90° C. and are therefore in the formof a coagulum or solid gel at 100° C. The plasticization state isobtained at temperatures in the range of 130 to 200° C., generallyaround a temperature of 145-170° C. for moisture levels during extrusionin the range of 50 to 80%, generally between 60 and 75%, and fat levelsin the dry product during the extrusion process in the range of 0 to40%, generally between 2 and 20%.

In principle, shear forces lead to reheating by friction. Pressure inthe extruder does not affect molecular interactions, particularlybetween proteins, but does allow high temperatures (130-300° C.) to beobtained without boiling or water vapour formation taking place.Surprisingly, the transition of thermo-coagulable proteins, especiallywhey proteins, through this plasticization stage confers on the mixturetransferred to the barrel an original viscosity, probably fairly fluid,in the order of 1000 to 500000 centipoises, which gives it a specifictexture during the cooling process in the die.

It is supposed that the mixture passes through a solid state at thebeginning of zone 10, through a liquid state in the melting zone 11(viscosity of 1000 to 100000 centipoises), a viscous state (viscosity of100000 to 500000 centipoises) in the uncooled zone 15 of the die 7, anuncooled zone in which progressive alignment of the mixture into fluidfibres probably takes place, and finally through a solid state in thecooled zone 16 of the die, a cooled zone in which fibres tending towardsthe solid state are formed.

During the plasticization process, proteins, particularly whey proteins,undergo a change in structure with a new structure emerging under thecombined effect of the cooling and shear forces applied in the die. Theconstituents of the mixture, especially whey proteins, rearrange in theform of a macroscopic and microscopic structure, consisting ofsuperimposed layers of aligned or tangled fibres with multipleramifications, and possibly even fibres arranged in the form ofV-shapes. These fibres are interchangeably referred to as ultrafibres orramified network fibres in the text.

The products 17 obtained by means of the above-described process willnow be outlined. On being discharged from the die 7, the productobtained 17 prior any further treatment being carried out, for examplecutting or tearing, is in the form of a roll 18, for example cylindricalwith a diameter similar to the diameter of the die in the case of a diewith a circular section, produced continuously if a continuous processis used. This roll 18 contains a set of fibres which can be separated,for example manually, into bundles of fibres, and even individually intoultrafibres. Fibres typically have a diameter that depends on the rawmaterials used and the operating conditions within the barrel andextruder die. Before treatment such as chopping, fibres can be quitelong, in the range of several centimeters, for example 4 to 5centimeters.

Under high magnification, for example ×50, of the product 17 shows thatthe fibre structure visible in the product at the macroscopic level isalso found at the microscopic level. This structure is similar to afractal, self-repeating structure, in other words fibre ramificationsappear to be infinite, in the same way as a hydrographic network.Ramifications continue towards the infinitely small: the same ramifiedstructure is perceived at each level of magnification. This extremelyfine fibre structure is also similar to that of striated skeletal muscleof mammals, consisting of a cascade of filament, microfilaments andfibrils. They are called “ultrafibres” because of their extremely finestructure.

At present, the largest fibres are at least 5 to 20 cm long with adiameter of 0.5 to 2 mm, if not in the order of cm for dies with adiameter of 20 to 30 mm. Associated fibres can be very small, to justwithin the limits of visual perception, in other words 1 to 2 mm longwith a diameter of 0.02 to 0.1 mm. It is assumed that this fibre networkcontinues down to the molecular level.

Depending on the composition of the initial mixture placed in theextruder and the operating conditions of the extruder, particularlytemperature and pressure conditions, a large range of aligned texturesis obtained. This fibre structure leads to rheological and organolepticproperties specific to the product and its derivatives, difficult tocharacterise instrumentally. A sample of fibres with a diameter of 30 mmand a length of 25 mm has an elasticity that is similar to that ofsynthetic viscoelastic compounds: relaxation coefficient of 60 to 90%,compared to 100% for rubber. The man skilled in the art is aware thathuman sensory perception is such that sizes in the order of 10 μm aredetected in the mouth. FIGS. 3 to 6 show the extruded product with afibrous structure.

According to one mode of application, the products leaving the dieundergo later treatment and are used as base materials or ingredientsfor a wide range of food preparations, typically incorporated at a rateof 15 to 70% in these preparations. According to one mode ofapplication, the extruded product undergoes chopping by means of achopper and/or cutting, crushing, tearing, shredding, etc., so as toobtain chopped fibres forming flakes or bundles. These flakes can bevery small in size, to within the limits required for mechanicalseparation of fibres. These chopped fibres or ultrafibres are mixed witha variety of other culinary ingredients, such as cheese, milk, cereals,starch, spices and seasoning to form a mixture. The composition of thismixture varies depending on the desired fibre-based final product. FIGS.7 and 8 shows a food preparation 19 containing a matrix 20 incorporatingbundles 21. FIG. 9 shows visible fibres 22 in this matrix 20.

Derivative products include, for example, sandwiches, snacks,preparations for ready-made meals, burger- or sausage-shaped cheeseproducts. In one mode of application, the mixture is shaped, for exampleby mechanical forming in a shaper, under careful hygiene monitoring.According to another application, the mixture is shaped in piping whichundergoes pasteurisation, slicing and, in some cases, coating ordecoration steps. The resulting products can, for example, be cooked inmoulds, removed from the mould or not, then packaged. These products canalso be used as raw materials for other culinary preparations afterfrying, baking, pasteurisation, sterilisation and other steps.

A few examples are given below of derivative culinary preparationsincorporating the product obtained from the extruder, a product based onwhey proteins and with a fibrous texture. This product is called“textured whey proteins” in the examples below.

PREPARATION EXAMPLES

Preparation example no. 1: formulation of a reconstituted steak usingtextured whey proteins (40%), Emmental (13%), Gouda (7%), Cheddar (5%),whole pasteurised milk (18%), cassava starch (3%), cereal flakes (8%),sodium caseinate (2%), water (3%) and spices (1%). The preparation ismixed in a blender, shaped, decorated and browned in the oven.

Preparation example no. 2: formulation and production of meat-freesausages using textured whey proteins (77%), Cheddar (10%),large-grained cassava starch (6%), sunflower oil (3%), various otheringredients (3%) and spices (1%). The preparation is churned undervacuum, introduced into the piping and steam cooked.

Preparation example no. 3: formulation and production of breaded nuggetsusing textured whey proteins (25%), Emmental (14%), Gouda (14%),breadcrumbs (13%), water (19%), potato starch (11%), milk proteins (3%)and spices (1%). The mixture is prepared in the cutter, shaped, coated,rolled in flour and breadcrumbs and fried in oil.

Preparation example no. 4: formulation and production of a culinaryingredient rich in milk proteins for addition to salads, starters,savoury stuffing and fillings, soups and gratins using textured wheyproteins (85%), pasteurised whole milk based spice marinade (12%), salt(1%), herbs and seasoning (2%). The preparation is churned under vacuum.

Preparation example no. 5: formulation and production of a sweet pancakeusing textured whey proteins (55%), dried fruit (12%), wheat-flour(12%), toasted cereal flakes (8%), sugar (7%), milk (5%) and vanillaextract (1%). The mixture is prepared in the cutter, measured,decorated, cooked on a hotplate and browned.

Preparation example no. 6: formulation and production of a sweet spreadusing textured whey proteins (25%), yoghurt (55%), fresh fruit (12%),pistachio (4%), sugar (3%) and a gelling agent (1%). The mixture isprepared in the cutter under vacuum and directly measured into pots.

Preparation example no. 7: formulation and production of a full-fatsavoury spread using textured whey proteins (15%), and/or full-fatfromage frais (80%), garlic extract (3%) and chives, salt and otherspices (2%). The preparation is prepared by mixing with an expandingagent with injection of gas, pumping and metering.

According to another application, it is possible to use the extruder tomanufacture a stuffed food product. A food stuffing material isintroduced through a coextrusion valve 23 opening into the extruder die.The stuffing material is, for example, added at a temperature belowabout 25° C. so as to cool down the interface with the cheese or dairypreparation extruded on the outside. The resulting product thereforeconsists of an outer layer of cheese or milk, whose texture is alignedin the direction of flow inside the die, and a food stuffing of varyingcomposition.

The coextrusion process can obviously be applied to a mixture consistingpurely of cheese or dairy raw materials but can also be applied to morecomplex formulations containing a small proportion of food ingredientsof diverse origin: wheat, soya, maize, peas, rice, vegetables, etc. Thestuffing can be a cheese or dairy preparation, for example a softcheese, or it can be a vegetable, meat, fish or seasoning basedstuffing.

It is also possible, after the extrusion/coextrusion step, to coat theproduct with a coating agent such as cereals or other edible solids. Inthis way, a product consisting of three layers of inner stuffing, acheese or dairy based envelope and a coating layer can be obtained. Theshape of the product can also be modified, depending on the cutting toolused 8, for example using a nipping cutter to produce a lengthenedcushion shape. In the case of a stuffing product obtained bycoextrusion, this application allows the stuffing to be entirely wrappedinside the product by mechanical processing of the product.

The raw materials used in the process will now be described in greaterdetail. The composition of the mixture added to the extruder is verysimilar to the product leaving the die. Water may be lost at the dieoutlet in some cases as a result of evaporation (about 1 to 5%). Drymatter in the mixture consists of 30 to 100% of dry matter originatingfrom whey.

When the whey-based material is a powder introduced through the fillingzone, the powder is obtained after concentration, ultrafiltration and/orseparation on preparatory chromatography columns then spray dried. Thewhey-based material introduced into the extruder in liquid form is, forexample, a concentrate obtained after ultrafiltration of diafiltrationof whey. In addition to the dry matter resulting from relatively dry orconcentrated whey, dry matter in the mixture includes, for example, fatsof vegetable or dairy origin (including butter and cream), liquid ordried egg white, concentrated or isolated vegetable proteins, vegetableflour, starches, alimentary hydrocolloids, spices and colouring. Thewhey can be a sweet whey from dairy or rennet casein, or sour whey fromcasein processing. The amount of casein in the dry matter is low,generally under 10%, which means dairy curds or complexes with a highproportion of casein cannot be used.

Vegetable proteins are, according to one application, wheat proteins,either pure or in the form of a mixture of glutens that can be breaded(glutens at 70-75% of protein, depending on the amount of starch andbran remaining during extraction leading to the production of a proteinconcentrate). In one application, a pea, lupin, soya or egg whiteprotein solution or powder is used instead of a wheat gluten powder.

A few examples of the detailed formulation of the mixture are givenbelow.

Formulation of Mixtures

Example 1

powdered whey protein concentrate containing 75% protein: 16%;

water: 66%;

sodium caseinate: 1.7%;

wheat protein concentrate containing 72% protein: 13%;

powdered egg white: 1.1%;

complex carbohydrates: 0.5%;

milk fats: 1%;

salt: 0.4%;

flavourings and seasoning: 0.3%;

Example 2

powdered whey protein concentrate containing 30% protein: 40%;

water: 30%;

powdered ultrafiltered natural casein 3.7%;

pea protein concentrate containing 68% protein: 6%;

wheat protein concentrate containing 72% protein: 6%;

powdered egg white: 10%;

complex carbohydrates: 1%;

milk fats: 2.5%;

salt: 0.7%;

flavourings and seasoning: 0.1%.

Example 3

whey cheese containing 10% protein: 78%;

powdered whey protein concentrate containing 80% protein: 18%;

sodium casein: 1%;

complex carbohydrates: 1%;

butter: 2%.

Example 4

lactoersum liquid protein concentrate containing 30% protein: 80%;

rennet casein: 3.2%;

pea protein concentrate containing 65% protein: 4%;

wheat protein concentrate containing 72% protein: 4%;

soya protein concentrate containing 67% protein: 4%;

powdered egg white: 1%;

complex carbohydrates: 1%;

milk fats: 2%;

salt: 0.7%;

flavouring and seasoning: 0.1%.

Example 5

water: 72%;

powdered whey protein isolate containing 90% protein: 9%;

calcium caseinate: 0.4%;

wheat protein concentrate containing 72% protein: 15%;

complex carbohydrates: 1%;

peanut oil: 2%;

salt: 0.6%

Example 6

water: 70%;

powdered whey protein concentrate containing 80% protein: 26.3%;

sodium caseinate: 0.3%;

complex carbohydrates: 0.9%;

butter: 2.5%.

Example 7

water: 61%;

powdered whey protein concentrate containing 82% protein: 23%;

wheat protein concentrate containing 12% protein: 13%;

powdered egg white: 1%;

spices (1%), vegetable fats (0.5%), salt (0.5%)

The description of the invention is merely exemplary in nature and,thus, variations that do not depart from the gist of the invention areintended to be within the scope of the invention. Such variations arenot to be regarded as a departure from the spirit and scope of theinvention.

What is claimed is:
 1. A food product obtained by extrusion baking of amixture of dairy or cheese origin which includes dry matter comprisingwhey proteins having an aligned fibrous structure, the fibres forming anetwork of macroscopic fibres whose diameters are in the order of 0.1 mmto 1 mm, ramified into microscopic fibres with diameters in the order of1 μm to 0.1 mm.
 2. The product according to claim 1 wherein the drymatter in the product consists of 30% to 100% of dry matter originatingfrom whey.
 3. The product according to claim 1 comprising 15 to 50% ofdry matter and typically 25 to 40%, the dry matter including at least35% of total proteins.
 4. The product according to claim 1 wherein thewhey dry matter is selected from the group consisting of isolatedproteins, concentrated proteins, dried whole whey, dried whey fractions,lactose, milk fats, lactoferrin, calcium, milk minerals, milk fractionsand mixtures thereof.
 5. The product according to claim 1 furthercomprising protein fractions selected from the group consisting ofcasein, caseinates, cheese, dried milk, concentrated milk and mixturesthereof, wherein the dry matter from the product comprises at least 10%casein.
 6. The product according to claim 1 further comprising non-dairyproteins selected from the group consisting of concentrated vegetableproteins, isolated vegetable proteins, wheat, soya, pea gluten, liquidegg white, dry egg white and mixtures thereof, wherein non-dairyproteins represent 0 to 70% of the mixture's dry matter.
 7. The productaccording to claim 6 wherein non-dairy proteins represent 20 to 50% ofthe mixture's dry matter.
 8. A food preparation incorporating a productaccording to claim 1 added to various ingredients selected from a groupcomprising cheeses; milk and derivative products further consisting offromage blanc, yoghurt, cream, butter, milk powder; cereals; starches;flour; semolina; spices; seasoning; pieces of meat; pieces of fish;vegetables; fruits and dried fruits; sugar-containing ingredientsfurther including sugar and honey; fats and flavouring; so as to formvarious food products selected from the group comprising ready-mademeals, sandwiches, children's snacks, breakfast products, cookingingredients, snack foods, shaped cheese products, vegetarian products,spreads, pate and cooking ingredients.
 9. The food preparation accordingto claim 8 further comprising a matrix selected from the groupconsisting of fibres, bundles of fibres, and combinations thereof, withsizes in the range of millimeters or centimeters, with the preparationhaving dimensions in the order of a few centimeters.
 10. The foodpreparation according to claim 8 wherein the food is shaped by methodsselected from the group comprising mechanical forming, metering, shapingin moulds and piping, followed by pasteurisation and slicing, whereinthe preparation obtained can be decorated, stamped, cooked, pre-cooked,pasteurised, sterilised and packaged.
 11. Food preparation according toclaim 8 further comprising an item selected from the group consisting ofsalts, spices, seasoning, flavouring, oil, other fats, an aciditycorrector such as lactic acid and combinations thereof.
 12. A filledfood preparation containing a product according to claim 1 whichencloses a filling product selected from dairy and non-diary products.13. A coated food preparation containing a product according to claim 1enclosed by a coating product selected from dairy and non-dairyproducts.
 14. An extrusion baked food preparation comprising a dairycomponent including dry matter further comprising whey proteins with afibrous structure wherein the fibers form a network of initial fiberswhose diameters are in the order of about 0.1 mm to 1 mm, modified intosubsequent fibers with diameters in the order of about 1 μm to 0.1 mm.15. The extrusion based food preparation according to claim 14 whereinthe dry matter in the product consists of 30% to 100% of dry matteroriginating from whey.
 16. The extrusion based food preparationaccording to claim 14 comprising 15 to 50% of dry matter, the dry matterincluding at least 35% of total proteins.
 17. The extrusion based foodpreparation according to claim 16 comprising 25 to 40% of dry matter.18. The extrusion based food preparation according to claim 14 whereinthe whey dry matter is selected from the group comprising isolatedproteins, concentrated proteins, dried whole whey, dried whey fractions,lactose, milk fats, lactoferrin, calcium, milk minerals, milk fractionsand mixtures thereof.
 19. The extrusion based food preparation accordingto claim 14 further comprising protein fractions selected from the groupcomprising casein, caseinates, cheese, dried milk, concentrated milk andmixtures thereof, wherein dry matter from the product is comprised of atleast 10% casein.
 20. The extrusion based food preparation according toclaim 14 further comprising non-dairy proteins selected from the groupconsisting of concentrated vegetable proteins, isolated vegetableproteins, wheat, soya, pea gluten, liquid egg white, dry egg white andmixtures thereof, wherein non-dairy proteins representing 0 to 70% ofthe mixture's dry matter.
 21. The extrusion based food preparationaccording to claim 14 wherein non-dairy proteins represent 20 to 50% ofthe mixture's dry matter.
 22. The extrusion based food preparationaccording to claim 14 added to various ingredient selected from thegroup comprising cheeses; milk and derivative products furtherconsisting of fromage blanc, yoghurt, cream, butter, milk powder;cereals; starches; flour; semolina; spices; seasoning; pieces of meat;pieces of fish; vegetables; fruits and dried fruits; sugar-containingingredients further including sugar, and honey; fats and flavouring; soas to form various food products selected from the group consisting ofready-made meals, sandwiches, children's snacks, breakfast products,cooking ingredients, snack foods, shaped cheese products, vegetarianproducts, spreads, pate and cooking ingredients.
 23. The extrusion basedfood preparation according to claim 14 comprising a matrix selected fromthe group consisting of fibres, bundles of fibres, and combinationsthereof with sizes less than 20 centimeters.
 24. The extrusion basedfood preparation according to claim 14 wherein the food is shaped bymethods selected from the group comprising mechanical forming, metering,shaping in moulds and piping, followed by pasteurisation and slicing,wherein the preparation obtained can be decorated, stamped, cooked,pre-cooked, pasteurised, sterilised and packaged.
 25. The extrusionbased food preparation according to claim 14 further comprising an itemselected from the group consisting of salts, spices, seasoning,flavouring, oil, other fats, an acidity corrector such as lactic acidand combinations thereof.
 26. The extrusion based food preparationaccording to claim 14 further comprising a filling selected from dairyproducts.
 27. The extrusion based food preparation according to claim 14further comprising a coating substantially enclosing the foodpreparation.
 28. A coated extrusion based food preparation comprising: afood product having a dairy component including dry matter, the drymatter including whey proteins with a network of macroscopic fiberswhose diameters are in the order of about 0.1 mm to 1 mm, ramified intomicroscopic fibers with diameters in the order of about 1 μm to 0.1 mm;and a coating substantially enclosing the food product.
 29. The coatedextrusion based food preparation according to claim 28 wherein thecoating is selected from a group comprising dairy products.
 30. Thecoated extrusion based food preparation according to claim 28 whereinthe dry matter in the product consists of 30% to 100% of dry matteroriginating from whey.
 31. The coated extrusion based food preparationaccording to claim 28 added to various ingredient selected from thegroup comprising cheeses; milk and derivative products furtherconsisting of fromage blanc, yoghurt, cream, butter, milk powder;cereals; starches; flour; semolina; spices; seasoning; pieces of meat;pieces of fish; vegetables; fruits and dried fruits; sugar-containingingredients further including sugar, and honey; fats and flavouring; soas to form various food products selected from the group consisting ofready-made meals, sandwiches, children's snacks, breakfast products,cooking ingredients, snack foods, shaped cheese products, vegetarianproducts, spreads, pate and cooking ingredients.
 32. The coatedextrusion based food preparation according to claim 28 wherein the foodis shaped by methods selected from the group consisting of mechanicalforming, metering, shaping in moulds and piping, followed bypasteurisation and slicing, wherein the preparation obtained isdecorated, stamped, cooked, pre-cooked, pasteurised, sterilised andpackaged.
 33. The coated extrusion based food preparation according toclaim 28 enclosing a filling selected from dairy products.